1. Field of the Invention
The present invention relates to a service plug which opens an electric circuit to cut off the circuit.
2. Description of the Related Art
Electric vehicles have been considered more and more as means for reducing exhaust gas discharged from vehicles with internal combustion engines to the environment. Since an electric vehicle obtains its driving force by driving electric motors, a battery constituting an electric power supply is installed in the electric vehicle. A high voltage circuit includes the battery, and since it is heavy, the battery is stored under the floor of the vehicle to thereby help lower the center of gravity of the vehicle. In the electric vehicle, in servicing the vehicle for maintenance, the high voltage circuit needs to be cut off in order to prevent a mechanic from being subjected to an electric shock. Because of this, a service plug for cutting off the high voltage circuit is provided on the electric vehicle. Namely, in the high voltage circuit including the battery, by a short-circuit plug body being inserted into a base member of the service plug when the electric vehicle is in use, the high voltage circuit is established, whereas by the plug body being removed from the base member when the electric vehicle is serviced for maintenance, the circuit is opened, whereby the high voltage circuit is made to be cut off.
A short-circuit terminal is provided on the plug body, and the plug body is fitted in the base member side so that the short-circuit terminal is inserted into a circuit terminal provided on a vehicle body, whereby the high voltage circuit is put into a short-circuited state. When cutting off the high voltage circuit, for example, at the time of servicing the electric vehicle for maintenance, the plug body is removed so that the short-circuit terminal is removed from the circuit terminal. After the maintenance service of the vehicle has been completed, the plug body is fitted back into the base member so that the high voltage circuit is restored from the cut-off state.
Normally, the plug body of the service plug stays fitted in the base member, and an easy removal of the plug body from the base member has to be avoided. Because of this, the service plug is installed in a position which can easily be accessed from an interior of the vehicle body (a position where the service plug cannot be removed from the outside of the vehicle body) and which becomes invisible from occupants of the vehicle. In the case of the battery being installed underneath the floor, the service plug is installed on the floor panel side under a seat cushion, and when the plug body has to be detached and attached back for maintenance service or the like, necessary work is performed within a space defined under the seat cushion.
Since the detachment and attachment of the service plug requires necessary work to be carried out within the limited space, good workability has been desired, and this is particularly true in inserting the plug body back into the base member. Because of this, there has been proposed a service plug in which a pair of guide walls are provided on a surface of a case member on a circuit terminal side in such a manner as to project therefrom in a confronting fashion, a guide groove extending in an inserting direction of a plug body (an inserting direction of a short-circuit terminal) is formed on each of the guide walls, a boss portion of the plug body is positioned from above the guide grooves, and the plug body is inserted along the guide grooves from above the guide walls (for example, refer to JP-A-10-144429).
In the related-art service plug, since the position of the plug body is restricted by the pair of guide walls, the plug body can be positioned properly relative to the base member even in a space defined under a seat cushion and made difficult to be visualized, thereby making it possible to insert the short-circuit terminal in the circuit terminal well.
In the related-art service plug, since the plug body needs to be moved to the position of the guide walls which lies upwards in the inserting direction of the short-circuit terminal, a gap which is equal to or larger than what results from the addition of a height of the guide walls and a height of the plug body becomes necessary between the floor panel and a lower surface of the seat cushion. Because of this, the related-art service plug cannot be used in a narrow gap or space, and in the event that the service plug is installed under the seat cushion, the related-art service plug can currently be used only on a limited number of model lines. Although the service plug can be installed in the limited space by reducing the height of the guide walls, the restriction of the plug body becomes insufficient, and hence, the short-circuit terminal cannot be inserted well in the circuit terminal.